Vascular/venous access devices for introducing catheters into a patient's vascular system are well known in the prior art. One of the most common of such devices comprises a through-the-needle catheter which is inserted into an anatomical passage through the use of cannula. The cannula itself typically comprises an elongate, metal needle which is inserted into the anatomical passage, with the catheter subsequently being advanced therethrough into the passage.
A common problem associated with the use of such prior art through-the-needle catheter systems arises during the removal of the cannula from the anatomical passage subsequent to the introduction of the catheter thereinto. Since, as previously indicated, the cannula typically comprises a rigid metal needle, it is desirable to immediately remove the cannula from within the anatomical passage subsequent to the advancement of the catheter thereinto to minimize trauma to the passage caused by the cannula's rigid structure and sharp piercing tip. However, once the catheter has been inserted into the anatomical passage, the cannula can typically only be removed from therewithin by retracting the same upwardly along the catheter, thereby undesirably exposing both the patient and the attendant medical personnel to accidental contact with the cannula, and more particularly the piercing tip of the needle.
In recognition of the problems and risks associated with the use of through-the-needle catheter systems, there is also known in the prior art over-the-needle catheter systems which have become widely utilized for venous/vascular access applications. In prior art over-the-needle catheter systems, a thin catheter having a hub attached to its proximal end is advanced over a rigid cannula, such as a needle, with the cannula and catheter being simultaneously inserted into a desired anatomical passage of a patient. Once the cannula and accompanying catheter have been introduced into the passage, the cannula is typically withdrawn from within the catheter interior, thus leaving the catheter operatively disposed within the passage. Thereafter, the hub mounted to the proximal end of the catheter may be used to fluidly connect the same to an infusion line or device.
A significant problem commonly associated with prior art over-the-needle catheter systems is that such catheters tend to travel axially (i.e., proximally) away from the distal piercing tip of the needle during the insertion process, thus collapsing the catheter. In this respect, the skin and tissue of the patient tend to resist the introduction of the distal end or tip of the catheter therethrough, thus pushing the distal end proximally away from the distal piercing tip of the introducer needle. Such proximal movement wrinkles the catheter in a bellows-like manner along the needle as the same is urged through the skin and tissue, with the distal end of the catheter traveling proximally away from the distal piercing tip of the needle.
Thus, such contemporary, prior art over-the-needle catheters must possess sufficient rigidity to prevent the same from traveling proximally relative to the cannula or needle upon which they are operatively positioned during the process of insertion into the anatomical passage. Because of the need for such rigidity, prior art over-the-needle catheters are typically incapable of being inserted through a substantial length of an anatomical passage (e.g., a vein or artery) without creating a relatively high risk of trauma and/or puncture.
In view of the foregoing, prior art over-the-needle catheters, though proving generally suitable for their intended purposes, have been found to possess deficiencies which detract from there overall effectiveness and reliability. As such, there exists a need in the prior art for an improved over-the-needle catheter which is not susceptible to collapsing or compressing during the process of insertion into an anatomical passage, yet is not so rigid so as to potentially cause trauma to the passage into which it is advanced.